How to test MOSFET for graphics card

okay today we're going to be testing a couple of mosfets for a video card typically using a video card there we're going to be testing this one here's the part number at the bottom and then we're going to be testing this guy and the part numbers at the bottom and the reason why i'm choosing these two is because the pin out is a little bit different uh they look nearly identical they seem to be identical and it could be very confusing so you want to be really careful when you choosing an alternative mosfet for your application so how do we go about testing these things basically we need a multimeter and we need to set this thing in a diode mode and so one thing you have to remember is that black opens which means contacts open there will be kilo ohms of resistance between the two contacts the red one closes and which means the contacts are going to be near zero ohms so the red one always goes to source and the black one always goes to drain and so and then you either then you open it or close it by touching the gate with either one of the probes so this particular mosfet right here that we're looking at right now its source is this guy here so we have two sources and two gates and two drains in here so [Music] look at the pin out which one is the source which one's the drain which one's the gate so source one so i put positive on the source drain is going to be here and you can see that there's some kind of a reading which is really odd reading because it's kind of charging and discharging so let's go ahead and like i said we open with the black one so let's touch the gate we touch the gate so now it reads open as a matter of fact we can change to resistance mode and check these two connectors check these two pins and we are reading half a mega ohm 500 some kilo kilo ohms so okay let's go back to diode mode again we're still open so if i want to close this i got to put this right there see without moving the black wire i just touched the gate with the red one and the connection is now closed as a matter of fact we can check the multimeter into the continuity test attach these pads zero ohms okay okay now let's move on to the one below exact same story different layout be very careful uh i'm going to flip my leads now don't get confused the reason why is because the source here is this pin here i will show it to you on the screen right there the source is this is this pin right there okay and then so the source one drain one and this is our gate right next to the source okay so let's go back in here and test it so red one goes to source black one goes to drain and we read short circuit as a matter of fact let's check with the resistance measuring we are short circuit okay so let's open this we're keeping our black wire no our red wire on the source and we're touching the gate it's a little tricky and hopefully i did it right yep it is now open let's double check with the resistance we are reading 76 kilo ohms so depending on the model and the ratings there will be there will be different resistance either open or closed but the bottom line is the red one is always goes on source and then the black one goes to drain and then if you want to open the connection you use the black one if you want to close the connection or short circuit it you use the red one okay so now let's flip this guy over okay now so that it'll be a little bit easier for you to understand maybe this time so again again this is going to be source number two and this is going to be drain number two so what do we have here we have an open connection uh this one's open so no connection in between there are kilo ohms in between 76 kilo ohms right now so if i touch let me put let me leave the black one on there so if i touch the gate with the red one it'll be closed there we go we got zero let's check we got zero so all these three pins they are all drains okay they're all connected to one to one another same thing with this guy here with the exception of we have source that's on these three pins on the top and the drain is actually here so don't get confused look at the schematic so put the red one on the source and the black one i'm sorry on the drain so we read short circuit so let's open it what do we know what do we open it with we opened it with black so we keep that on there and then we touch touch the gate we touch the gate with the black one while holding the red one on the source now let's check and now it is open how do we close it we use the red wire and we touch the gate now let's check and we're now closed how do we open it again black wire black wire there and now it's open so this is it i hope you learned something today and thank you for watching please consider subscribing liking and commenting below have a blessed day bye bye

Channel: northwestrepair

Views: 11,613

Keywords: how to repair, how to fix, how to diagnose, how to identify, how to find out, graphics card, gpu, test, diagnose, working

Id: gVwFSu2WDv4

Length: 7min 17sec (437 seconds)

Published: Wed Jul 20 2022